Suzuki 2 Strokes

Some models of GT750 have the engine casting channel between the rear top collar spacer of the engine mounts cut down into a 'V' shape. If anyone has an engine with this design can you check the number on it for year of manufacture.
Ian is building a reference for all things buffalo and this info will help identify these 'rare' cases to the year of manufacture.

Went through a few of Fred's collection, and that 'v' notch case looks to be a 1977 specific variant. Looking at the parts lists, the 'B' model had its own crankcase part number (11300-31852), so I'm guessing that is (perhaps one of the things) changed.